UPPCL AE 2019

Question 1
Consider the binary relation R=(x,y),(x,z),(z,x),(z,y)on the set x,y,z. Which of the following is TRUE?
A
R is neither symmetric nor antisymmetric
B
R is both symmetric and anti-symmetric
C
R is symmetric but not antisymmetric
D
R is not symmetric but anti-symmetric
Question 1 Explanation: 
Let A be a set in which the relation R is defined. Then R is said to be a symmetric relation, if (a, b) ∈ R ⇒ (b, a) ∈ R, that is, aRb ⇒ bRa for all (a, b) ∈ R. The relation R is antisymmetric, specifically for all a and b in A; if R(x, y) with x ≠ y, then R(y, x) must not hold. Or similarly, if R(x, y) and R(y, x), then x = y. Therefore, when (x,y) is in relation to R, then (y, x) is not. Here, x and y are nothing but the elements of set A.
Question 2
Which type of address is 255.255.255.255 according to IPv4 addressing?
A
Limited broadcast address
B
Multicast address
C
Direct broadcast address
D
Loopback address
Question 2 Explanation: 
A broadcast address is a network address used to transmit to all devices connected to a multiple-access communications network. A message sent to a broadcast address may be received by all network-attached hosts. A multicast address is used to address a specific group of devices, and a unicast address is used to address a single device. IPv4 address 255.255.255.255 is used as a limited broadcast address. Limited broadcast address 255.255.255.255 can appear as the only destination address in the IPv4 header. Limited broadcast is a type of broadcast which is limited to the Local Area Network (LAN). Routers will not forward limited broadcast IPv4 datagram packets because these broadcasts are not relevant to other networks and cause flooding everywhere in the Internet. So, the scope of limited broadcasts is limited to the Local Area Network (LAN).
Question 3
Which of the following memory types is volatile in nature?
A
Compact disk
B
Magnetic disk
C
ROM
D
RAM
Question 3 Explanation: 
Volatile memory, in contrast to non-volatile memory, is computer memory that requires power to maintain the stored information; it retains its contents while powered on but when the power is interrupted, the stored data is quickly lost. Volatile memory has several uses including as primary storage. In addition to usually being faster than forms of mass storage such as a hard disk drive, volatility can protect sensitive information, as it becomes unavailable on power-down. Most general-purpose random-access memory (RAM) is volatile
Question 4
In Two-phase locking protocol, each transaction issues lock and unlock requests in ______ phases.
A
Four
B
Five
C
Three
D
Two
Question 4 Explanation: 
In databases and transaction processing, two-phase locking (2PL) is a concurrency control method that guarantees serializability. It is also the name of the resulting set of database transaction schedules (histories). The protocol uses locks, applied by a transaction to data, which may block (interpreted as signals to stop) other transactions from accessing the same data during the transaction's life. By the 2PL protocol, locks are applied and removed in two phases: Expanding phase: locks are acquired and no locks are released. Shrinking phase: locks are released and no locks are acquired.
Question 5
Which of the following can be considered as a weak entity?
A
Edition
B
Book
C
Publisher
D
Author
Question 5 Explanation: 
In a relational database, a weak entity is an entity that cannot be uniquely identified by its attributes alone; therefore, it must use a foreign key in conjunction with its attributes to create a primary key.
Question 6
Consider the following relation schema: Product (id, name, price) What will be the output of the following SQL code? SELECT max(price) FROM Product WHERE price < (SELECT max(price) FROM Product);
A
Highest price of a product
B
Lowest price of a product
C
Second highest price of a product
D
Second lowest price of a product
Question 6 Explanation: 
Second highest price of a product
Question 7
Which of the following represents the language corresponding to the regular expression r = (aa) * (bb) * b?
A
L(r)=a2nb2m:n0,m0
B
L(r)=a2nb2m:n1,m1
C
L(r)=a2nb2m+1:n0,m0
D
L(r)=a2nb2m+1:n1,m1
Question 8
In Classful addressing for class A, how many valid maximum possible network ids can exist?
A
129
B
127
C
128
D
126
Question 9
Match the following:
A. SLR(1) 1. Medium powerful & medium cost
B. LALR(1) 2. Less powerful and less cost
C. CLR(1) 3. More powerful and more costly
A
A-1, B-3, C-2
B
A-2, B-1, C-3
C
A-1, B-2, C-3
D
A-3, B-2, C-1
Question 10
Which of the following statements is/are FALSE?
(i) By definition a relation schema is in first normal form.
(ii) A relation schema which is in third normal form is definitely in BCNF.
A
Only (ii)
B
Neither (i) nor (ii)
C
Both (i) and (ii)
D
Only (i)
Question 11
Which of the following statements are FALSE?
(i) The total length of the UDP header is 8 bytes.
(ii) DNS makes use of UDP.
(iii) The checksum field in UDP is assigned 8 bits.
(iv) UDP requires connection establishment and connection termination between sender and receiver
A
Only (i) and (iii)
B
Only (i) and (ii)
C
Only (iii) and (iv)
D
Only (ii) and (iv)
Question 12
Let R(A,B,C,D) be a relation schema and F=ABC,ABD,BCbe the set of functional dependencies defined over R. Which of the following represents the closure of the attribute set B?
A
{A, C, D}
B
{B, C}
C
{B}
D
{A, B, C}
Question 13
What is the sum of the Hexadecimal numbers (FF)16 and (BA)16?
A
(B9)16
B
(139)16
C
(1B9)16
D
(2B9)16
Question 14
Which of the following represents (-0.75)10 in IEEE 754 Single Precision (Binary32) Format?
A